1. Field of the Invention
This invention relates to a slide fastener. In particular it relates to a slide fastener in which the slider can be moved past an end stop for stopping the sliding movement of the slider in order to allow opening of the slide fastener.
2. Description of the Related Art
Conventional slide fasteners comprise a pair of stringers, each stringer being comprised of a tape and coupling elements, and a slider which can be moved along the coupling elements of the stringers to engage and disengage the coupling elements. A top end stop is placed at the upper end of one or both of the stringers to prevent the slider from moving beyond the coupling elements on one or both stringers, which would otherwise allow unpeeling of the coupling elements and separation of the stringers. In certain situations it is advantageous that the slider can be moved beyond a top end stop on one of the stringers by applying additional force, so that the stringers can be quickly separated. Such a top end stop is sometimes called a “top open” or a releasing end stop.
In normal operation, a releasing end stop impedes further upward movement of the slider, to maintain the coupling elements in an engaged state. If an increased forced is applied to the slider to move the slider upwards, the slider is forced past the releasing end stop to allow quick opening of the slide fastener by unpeeling the engaged elements below the slider. In this way, the releasing end stop can be said to impede, but not prevent, passage of the slide fastener. Preferably the releasing end stop is provided on one tape only. The elements on the other tape extend beyond the level of the releasing end stop to hold the slider on the other tape. After the tapes are separated, the slider is slid down to the bottom of the other tape to allow the fastener to be refastened in the usual way.
One such arrangement is shown in U.S. Pat. No. 2,894,305. The releasing end stop has a spring member which abuts cooperating elements on the opposing tape to prevent movement of the slider past the releasing end stop. When additional force is applied to the slider, the spring yields to allow the end stop and the cooperating elements to close together and allow the slider to slide past the releasing end stop.
In GB-A-1 519 340 describes a slide fastener having a pair of cooperating releasing stops respectively mounted on opposed stringers. One of the end stops has a substantially annular shape, such that a portion of the top end stop can be deflected inwards to compress the top end stop when the top end stops are pushed together by the neck of the slider. A similar arrangement is used in Japanese publication 41-22065 and Taiwanese publication M245806 which each describe integrally formed releasing end stops having a deflectable or deformable portion which allows the end stop to be compressed when a suitable force is applied by the slider to the end stop.
Typically, a releasing end stop is provided in a slide fastener having injection moulded plastics elements, such as are manufactured by the current applicant under the trade mark VISLON. Suitable materials are preferably rigid and hardwearing so as to prolong the life of the coupling elements which are subject to the repeated sliding movement of the slider. It is preferable to use the same material for the top end stop as for the coupling elements, so as to simplify the manufacturing process. However, when made of relatively rigid material, the deformable portion must be relatively thin to allow it to deform, but it is still inherently hard or inflexible and thus is prone to breaking.
It is an object of this invention to provide a releasing end stop which overcomes these problems.